Method of making coated laminated paper



1943- P. s. BARNHART I 2,325,584

METHOD OF MAKING COATED LAMINATED PAPER Original Filed Feb. 1, 1937(baiz'ny Paper Paper (balmy INVENTOR Patented Aug. 3, 1943 METHOD OFMAKING COAT ED LAMINATED PAPER Philip S. Barnhart, Westfield, Mass,assignor to Westiield River Paper Company, Inc., Russell, Mass, acorporation of Massachusetts Original application February 1, 1937,Serial No.

123,334. Divided and this application February 2, 1940, Serial No.316,909

4 Claims. (01. 154-40) This inventionrelates to a method of makingcoated laminated paper, and this application is a division of myapplication Serial No. 123,334, filed Februaryl, 1937.

Laminated paper is well known in the art, having been used extensivelyfor various purposes. Two or more plie or sheets have been laminated inorder to gain additional strength, added weight, greater transparency,in the case of papers, such as glassine, and also to obtain moistureresistant properties.

ment or binder, which holds the sheet together, to

fuse, melt or soften, thus permitting the laminated sheets to separateduring the coating process.

It is not practical to coat the sheets first and then laminate themsince the coated surfaces Various laminating cements have been used,

. combinations, etc.

Coated papers have also become well known in the art, the coating beingapplied to gain various effects, such as gloss, better appearance,decorative effects and moisture resistant properties. These coatingshave been applied to one or both surfaces of sheets, such as sheets ofregenerated cellulose, glassine, cellulose acetate and other sheetmaterials, thus giving moisture resistant properties as well as theother effects above mentioned. Such sheets. have been coated withvarious solutions or lacquers, as solutions of nitrocellulose, resinsand plasticizers and wax combinations, resin and wax combinations,chlorinated rubber base lacquers, etc.

The same types of lacquers have also been used on opaque papers and itis possible to add to the lacquers coloring matter or pigments, alsometal owders, such as aluminum powder, bronze powder, and the like, togive decorative effects.

In order to further enhance the appearance and utility of laminatedsheets it has been found advantageous to coat the laminated sheet,either on one or both surfaces, with a coating solution which willenhance the moisture resistant properties of the sheet. There has been aconsiderable demand for. paper which has a greater moistureresistantproperty than can be secured by the usual laminated paper, such aslaminated glassine paper, or by a single sheet of coated glassine paper.This increased moisture proof property is particularly desirable whenthe paper is used as a wrapp ng for hygroscopic food products, such aspowdered extracts, powdered desserts, malted milk and similarsubstances.

Difficulties have been encountered in producing a coated laminated sheetsince coated papers are force dried, usually in ovens, and thedryingtemperature tends to cause the laminating cewould be subjected toabrasion during the laminating process, causing blemishesand scratchesand rendering the product unsaleable.

In my solution of the problem in coating a laminated paper, I employ acoating of lacquer solution or other thermoplastic compositioncontaining a solvent which evaporates and promotes drying of the coatinon the laminations at a temperature lowerthan the elevated temperaturewhich previously melted and rendered the cementing binder effective whenintegrating or bonding the sheets together in laminatedform preliminaryto coating it. In this Way I apply the coating as the last step in theprocess and thus avoid handling or machine treating of the finishedpaper after the decorative or moistureproof coating is applied.

This invention has for its salient object to provide a method ofmanufacturing a coated laminated sheet, so worked out that thelaminating cement or binder will not fuse or soften during the drying ofthe coating films, thus preventing the separation ofthe laminated sheet.

In other words, an object is to provide a method of manufacturing coatedlaminated paper in such a way that the application of heat to a coatingsolution on the paper, for drying the coating by evaporating the solventtherefrom, does not melt and loosen the binder used in previouslybonding the laminations into a unitary sheet.

Further objects of the invention will appear from the followingspecification taken in connec tion with the drawing which forms a partof this application and in which the single figure illustrates insection greatly enlarged section of a coated laminated sheet constructedin accordance with the invention.

The drawing illustrates in section a. laminated sheet comprising a pairof sheets i and 2 of paper which are laminated 01' secured together byan adhesive or cement or hinder 3. The laminated sheet is coated on bothsurfaces by coatings 4 and 5.

Although it is not the intention to limit the invention to anyparticular or specific ingredients for the binder and the coatingcompositiomcertain examples of binders and coating compositions will besetforth in order to give examples of sistance and adhesion and can bereadily applied 7 in the laminating operation.

A preferred binder may contain these ingredients in the followingproportions: Wax 40- 63%; rosin 20-45%; rubber 13-12%, and petrolatum Asa more specific example, these'ingredients may be combined as followszlWax 61%; rosin 27%; rubber 5%, and petrolatum 7%. Paramne wax having amelting point of 155 F. and petro-. latum having a melting point of 125F., are preferred.

The coating composition which has been found particularly desirable mayconsist of the following ingredients combined in the proportions stated:Chlorinated rubber 10-50%; resin 25-38%; parafline wax 2-7%, and aplasticizer, such as di-butyl phthalate, -21%. The resin which has beenfound particularly adaptable for such use comprise glycerol abietate -25and para coumarone 5-13%, The paraifine wax preferably has a meltingtemperature of 143-145 F.

As a still more specific example of a coating composition, theingredients above set forth may be combined as follows: Chlorinatedrubber 46% (65-68% chlorine); glycerol abietate 19%; parafllne wax 65di-butyl phthalate 16 5%,, and para coumarone 12%.

After these ingredients are combined in these approximate proportionsthe composition is dissolved in an suitable hydro-carbon solvent, such,as benzol, toluol, xylol, etc., to give a solution of the desiredviscosity.

In making the coated laminated sheet the sheets are first laminated inany well known manner by the use of a cement or binder which fuses at anelevated temperature and. has the characteristics setforth, andthereafter the laminated sheet is coated with the coating composition onone or both surfaces by passing the sheet through a coating machinehaving coating mechanism and having an oven in which the lowertemperature is maintained between 145-170 F., depending, of course, onthe fusion point or temperature of the cement between the laminated plieorsheets.

A laminated sheet so treated has an extremely high gloss, is flexible,transparent and has greatly increased moisture resistance properties.The coating solution or thermoplastic composition may consist of a heatsealing or thermoplastic base lacquer and, as stated, can be applied onon or both sides of the laminated sheet.'

Although various cements and coating compositions may be used, thefollowing essential or requirement must be adhered to,-namely, that thedrying temperature required for drying the coating composition must ,belower than the fusing, melting or softening temperature of the binder orcement used to laminate the sheets.

This invention is presented to fill the need for a useful method ofmaking'coated laminated paper. It will be understood how variousmodifications in construction, mode of operation, use and method, mayand often dooccur to others,

especially so after benefiting from knowledge of an invention;Accordingly, this disclosure is exemplary of the principles of theinvention and its equivalents without being-limited to the presentshowing thereof; I I

What I claim is:

1. A method of making a coated laminated product, consisting in unitingat least two sheets of glassine paper by applying a binder between theinner surface of the sheets, which binder comprises at least 40% wax,fusing the binder by heat at an elevated temperature to render iteffective in uniting said sheets, thereafter applying acoating ofthermoplastic base lacquer to at least one surface of the united sheets,and then drying theapplied coating by evaporating the solvent therefromat a temperature lower than that which previously fused the binder andwithout causing separation of the united sheets.

2. A method of making a substantially transparent coated laminatedproduct, comprising uniting sheets of glassine paper with a bindercomprising at least 40% wax which binder isfused and rendered effectiveby heat at an elevated temperature, thereafter applying an outer coatingof thermoplastic composition containing a volatile solvent tothelaminated paper, and

then drying the coated paper at a temperature binder.

4. A method of making a coated laminated product, comprising unitingsheets of glassine paper with a binder. containing 40% to 63% of waxwith 20% to 45% of rosin and 3% to 12% of rubber as well as 7% to 13% ofpetrolatum, which binder is' fused and rendered effective by heat. at anelevated temperature, thereafter employing a thermoplasticcomposition-consisting of 40% to 50% of chlorinated rubber with 25% to38% of resin and 2% to 7% of paraffine as well as 15% to 21% of di-butylphthalate together with a'volatile solvent and applying such compositionas a coating to the laminated p per, and then drying the coated paper ata temperature approximately between and F.. the latter temperature beinglower than that which previously fused the binder.

PHILIP s. BAR HARTQ

